FALLUJAH, IRAQ
— Dust-coated US forces are encircling the Iraqi rebel stronghold of Fallujah, awaiting final assault orders, as insurgents dramatically escalated their own attacks elsewhere in the Sunni triangle over the weekend, leaving more than 50 dead.

American aircraft and artillery bombarded targets in Fallujah as US commanders prepared for a major urban conflict that they compare in scope to the costly but victorious 1968 Vietnam battle for Hue City.

"This town is held by mugs, thugs, murderers, and terrorists," Lt. Gen. John Sattler, commander of the 1st Marine Expeditionary Unit, shouted to marines at a staging ground Sunday. "You know what your mission is. Go out there and get it done."

To deal with the stiffening rebellion - and an expected surge of attacks if US troops storm Fallujah - Iraq's Interim Prime Minister Iyad Allawi Sunday declared martial law for 60 days across much of the country.

More than 10,000 US troops are poised for the Fallujah fight. US intelligence estimates that up to 3,000 insurgents - with a core of several hundred well-trained foreign fighters waging an anti-American jihad, and led by Al Qaeda affiliate Abu Musab al- Zarqawi - have prepared layers of booby-trapped defenses that make heavy use of suicide car bombs and even entire buildings rigged to explode.

Six battalions of US Marines, backed up by Army tanks and armor and newly trained Iraqi troops, sealed off Fallujah at midday Sunday. Leaflets dropped in the city warned residents to leave by then, if they were to avoid the fight.

"This is the Hue City of our generation," says Lt. Col. Michael Ramos, commander of the 1st Battalion, 3rd Marines, which is expected to play a key role in Fallujah. In Hue in 1968, heavily outnumbered marines reversed one of the North Vietnamese gains, reclaiming the city block by block, in four weeks of combat that left more than 142 marines dead.

"My marines, once they are unleashed, will bring a decisive victory and closure to [the Fallujah] operation," says Colonel Ramos, from Dallas, Texas. "We will be deliberate in our violence against the terrorists and insurgents, and we will be deliberate in our mercy to Iraqi civilians and the innocent."

Warning from Kofi Annan

Political tension is already growing over the expected assault. UN Secretary General Kofi Annan on Friday warned that any assault on Fallujah could spark so much violence that elections slated for January could be impossible.

Clerics from Iraq's Sunni minority have vowed to boycott those elections, if US troops enter Fallujah. On Saturday, an open letter to the Iraqi people from 26 Saudi scholars and clerics said armed resistance to US and allied Iraqis is a "legitimate right."

"Fighting the occupiers is a duty for all those who are able," the fatwa, or religious edict read. "It is a jihad to push back the assailants."

It was political fallout over mounting casualties on both sides that caused the White House to stop a Marine offensive last April. That attack was hurriedly put together after four American contractors were killed and mutilated. By contrast, the current buildup has been carefully planned and rehearsed, and top brass estimate that today they are bringing three to five times more "combat power" to the front.

Marines entering Fallujah are prepared to treat every vehicle and building as a potential bomb. A weekend report in the London Times, from inside Fallujah, quotes insurgent commanders claiming that they have rigged 118 car bombs, and have 300 volunteer foreign suicide bombers lined up to take on advancing American units.

The Times reported that trenches have already been dug in Fallujah's cemeteries, "in preparation for hurried burials of 'martyrs' in white shrouds."

"Never send a marine where you can send a round," Capt. Gil Juarez advised his Light Armored Reconnaissance company, as final preparations got under way. "The enemy is crafty. We just have to be methodical, with techniques that work. Put steel on the target. We need not panic in the face of the enemy."

"You have to adhere forcefully to the rules of engagement," Captain Juarez told his armor platoon and team leaders. The rules, he said, are designed to strike only insurgent targets, not civilians.

"This is all one piece of a larger picture," says Juarez, from San Diego. "If we have a lance corporal [messing] that up, we could win the battle and lose the war. You in this room have to keep your marines on that."

Already, the battle of Fallujah has been waged since mid-summer, when US aircraft began nightly air strikes of suspect targets linked to Mr. Zarqawi's network. Residents have described numerous civilian casualties and damage, including destruction of the city's most popular kebab restaurant.

Insurgents ignore feint attack

The military estimates that just 50,000 people remain. Among them are insurgents who barely reacted overnight Friday, when scores of armored vehicles launched a feint operation to probe the insurgent response.

"It looks like our little fake attack didn't work," said a machine gunner, waiting patiently in the dark in the back of an armored vehicle, just a few hundred yards north of the city limit.

Shortly thereafter, the marine radio chatter spoke of seeing a pair of three-man insurgent teams. One group had a rocket-propelled grenade and a rooftop forward observer with a mobile phone.

Tanks and armored vehicles fired at the railway station and at buildings on the northern outskirts. City lights blinked out for a time, then came back on. The next morning, Reuters reported that two civilians had been killed, and that a newly built, unused hospital had been hit. Weapons caches were also destroyed.

But a counterattack never came. "They didn't respond like we thought they would," Colonel Ramos said later. "They're smart. They're saving it up. They learned a lesson - they used to show themselves."

There is also concern that information about the offensive - which has been shared with officers of Iraqi forces, whose several thousand troops are to take part alongside US forces - may have been leaked. An Iraqi captain deserted on Saturday, after receiving a US battalion commander's briefing. He is a Kurd, and is not believed to have left to compromise the plan. US commanders say he may have been afraid to fight. Indeed, a number of Iraqi soldiers also did not show up over the weekend, echoing the performance of Iraqi troops last April, when units melted away at the outset of fighting.

"To be honest, it doesn't bother me [if insurgents] know [the plan], if it induces a bit of fear in their hearts," Ramos said Sunday. "I'd like them to sleep uneasy tonight, because tomorrow they'll be captured or dead."